This paper examines whether internal control audit is more effectively than internal review on improving financial report quality. We study the association between internal control audit/review report and accrual quality based on panel model and DID (difference in difference) model and we find：1) the companies that have receives an internal control audit report or internal control review report have higher accrual quality than the companies that havent received any internal attestation report; 2) the companies that have received an internal control audit report have higher accrual quality than the companies that have received an internal control review report. This research results prove that internal control audit is more effectively than internal control review and external oversight around internal control is necessary and effective.